1. Field of Invention
Aspects of this invention are related to measuring the inserted length of an endoscope, and more particularly to measuring the inserted length of an endoscope without an external position sensor at the body entry point of the endoscope.
2. Related Art
An endoscope is a medical instrument for visualizing the interior of a patient's body. Endoscopes have been used for a variety of medical diagnostic procedures and for a variety of medical interventional procedures.
Many different types of endoscopes are known. For example, one steerable endoscope has an elongated body with a steerable distal portion and an automatically controlled proximal portion. Such an endoscope is described in U.S. Pat. No. 6,468,203 B2, entitled “Steerable Endoscope and Improved Method of Insertion,” of Amir Belson issued on Oct. 22, 2002, which is incorporated herein by reference in its entirety.
A common problem with using an endoscope is determining the insertion depth of the endoscope during the procedure. One way to determine the insertion depth is to use an external position sensor at the entry point of the endoscope into the body of the patient. See for example, U.S. Patent Application Publication No. US 2007/0249901 A1 published on Oct. 25, 2007 for U.S. patent application Ser. No. 11/648,408, entitled “Instrument Having Radio Frequency Identification Systems and Method for Use,” of Ohline et al. filed on Dec. 28, 2006.